LXC snapshot backups

[decibel83]

Hi.
After upgrading to Proxmox VE 4 snapshots are not longer possible for LXC containers and they need to be suspended during the dump even if I am using a LVM storage with free space for snapshots in the volume group.
I know that the snapshot works with a ZFS storage, but I wish to understand if there is a way to make it work on the existing LVM storage.
Thanks!

 

[dietmar]

You need to use LVM-thin.

https://pve.proxmox.com/wiki/Storage:_LVM_Thin

 

[decibel83]

Thanks!
I was wrong when I told you that I am using the LVM storage.
I am using a dir storage on a LVM logical volume.
Is there a way to have snapshots backups on it without converting all containers to LVM?
I wish to maintain the directory storage to let me easily migrate containers through the cluster.
And... why snapshot backups are working for KVM virtual machines?

 

[dietmar]

I wish to maintain the directory storage to let me easily migrate containers through the cluster.

use ZFS ...

And... why snapshot backups are working for KVM virtual machines?

Because you can use the qcow2 file format with KVM, which support snapshots internally.

 

[decibel83]

use ZFS ...

Thanks.
But I already have an hardware RAID configured on all nodes, and using ZFS on hardware RAID is not advised (https://en.wikipedia.org/wiki/ZFS#ZFS_and_hardware_RAID).

Or do you advise me to create a striped ZFS pool on the LVM logical volume /dev/mapper/pve-data (which is now an ext4 partition which Proxmox is using as a directory storage)? So a single device on the ZFS pool?

And what about new machines (I will add 4 new nodes the next month)? Do you advise me not to use the hardware RAID and use ZFS mirrored for the whole system?

Thanks!

 

[decibel83]

Hi Dietmar,
I read the page at https://pve.proxmox.com/wiki/ZFS_on_Linux and https://forum.proxmox.com/threads/zfs-vs-hardware-raid.30243/, so I am about to convince myself to not use hardware RAID on the new nodes and install Proxmox directly on ZFS RAID1.
But what about existent nodes? Should I format and reinstall them from scratch deleting the RAID Hardware and configuring ZFS?
What do you think about?
Thanks!

 

[dietmar]

But what about existent nodes? Should I format and reinstall them from scratch deleting the RAID Hardware and configuring ZFS?
What do you think about?

Both LVM-thin and ZFS provides most features. I personally use both in production.

 

[decibel83]

Thanks.
But will I be able to easily move virtual machines from node to node?
Please forgive me for all these questions, but I was accustomed to snapshots on OpenVZ containers on LVM local storage and now that I don't have them on LXC containers I am trying to find the best solution I can, not worst than the one I was having before the upgrade to LXC.

 

[dietmar]

Please forgive me for all these questions, but I was accustomed to snapshots on OpenVZ containers on LVM local storage and now that I don't have them on LXC containers I am trying to find the best solution I can, not worst than the one I was having before the upgrade to LXC.

Not sure what you talk about. You have full container snapshots support with both LVM-thin and ZFS. You can also mount the container root file system, so it is really easy to access container files from the host even when you use LVM-thin. The old OpenVZ system did not provide snapshots on local storage - there was just a workaround to use slow LVM snapshots for backups ...

 

[decibel83]

Not sure what you talk about.

I mean, with qcow2 and raw files (and old OpenVZ private root) it was very simple to migrate virtual machines to another node (using the "migrate" function in the GUI or simply moving files through SSH).
How it works with ZFS or LVM-Thin storage?

 

[dietmar]

it was very simple to migrate virtual machines to another node (using the "migrate" function in the GUI or simply moving files through SSH).
How it works with ZFS or LVM-Thin storage?

You can still migrate VMs an containers, see 'qm migrate' and 'pct migrate' commands.